Deposition Area

Litho Area

Shamrock 19608 Sputtering System:

Up to Six Sputter Sources

DC/RF AC Process Modes

Integrated Ion Mill

No Shaper Shields

Flat Orbital Planetary

Integrated Magnetic Array

The Shamrock sputter tool is system of the type which found wide use in Seagate research and development centres. It is capable of processing up to 6" wafers. The system is full automatic and has a maximum capacity of 16 wafers, and can deposit on up to 4 wafers in one process at ambient temperature due to its planetary turntable geometry. Processing several wafers at once allows for high target efficiency while maintaining low growth rate for smoother films. Typical deposition rates in our system are less than 1A/s.

Chamber A of the system has 4 DC sputter guns, 2 DC/RF sputter guns and an ion gun. The flexibility of the system allows for alloys of up to 6 targets to be sputtered with good compositional control. An in-plane magnetic field can be used during deposition to set the easy axis of spin valve and tunnel junction samples. Typical base pressure of the system is below 10-7 Torr and operating pressure is in the mTorr regime. At present the system is configured to sputter metallic targets but due to its RF capabilities it is possible to sputter insulating materials such as oxides . The system also has the capability of sputtering under O2 for the creation of nano-oxide layers (NOL) and tunnel barrier oxides from Mg or Al targets.

The system comprises three independent chambers;

Cassette module (CM): loadlock capable of holding 16 wafers at a time

Transfer module (TM): fully computer controlled robotic platform based around the Genmark GB3 vacuum robot system, allows automatic transfer of wafers from CM to PM and also to chamber B and chambers C and D which are used to oxide barrier deposition and evaporation respectively, the transfer module also contains a Cs evaporation source for spin injection experiments

Chamber A (PM): process chamber with rotating turntable system with 4 "planets" for the processing of 4 wafers at one time, 6 sputter guns, ion milling sputtering under Ar and reactive O2 is available.

Chamber B: has 4 DC sputter guns, 2 DC/RF sputter guns and an ion gun. The flexibility of the system allows for alloys of up to 6 targets to be sputtered with good compositional control. An in-plane magnetic field can be used during deposition to set the easy axis of spin valve and tunnel junction samples. Typical base pressure of the system is below 10-7 Torr and operating pressure is in the mTorr regime. At present the system is configured to sputter metallic targets but due to its RF capabilities it is possible to sputter insulating materials such as oxides . The system also has the capability of sputtering under O2 for the creation of nano-oxide layers (NOL) and tunnel barrier oxides from Mg or Al targets.

The Shamrock is a very versatile system which allows for a lot of flexibility in terms of sample size and alloy deposition. It is mainly used for spin valve and magnetic tunnel junction electrode deposition (barrier deposition takes place in chamber B), but it has also been used to sputter Co2MnSi Heusler alloys and NiFeCr alloys from independent targets. It forms the core of our group's deposition facilities. In its complete form, it allows for DC metal sputtering with low roughness, high quality tunnel barrier deposition using the target-facing-target source on amorphous CoFeB electrodes in chamber B, high quality MgO and CoFeB evaporation in chamber C and D and in situ annealing under high magnetic field.

MANSE Related School of Physics/CRANN X-ray facilities

School of Physics and CRANN currently share three x-ray diffractometers. One Siemens D500 used for powder phase analysis by Schools of Physics, Pharmacy and Chemistry, one PANalytical X'Pert Pro (belonging to Prof. J. M. D. Coey's group) and a newly acquired BRUKER D8 Discover. Prof. I. Shvets' group furthermore maintains a high resolution triple axis BEDE diffractometer. Both the BRUKER and the PANalytical are equipped with 1D state of the art detectors allowing for fast phase analysis and reciprocal space mapping. This assures a high throughput when optimizing growth parameters of thin films as well as powder samples. The PANalytical can furthermore be used for grazing incidence x-ray reflectivity to obtain information on thin film thickness and interface roughness of both single layers and stacks, in particular samples grown for spintronics applications such as MgO-based magnetic tunnel junctions, spin valves and nano pillars for spin torque measurements. The diffractometer is equipped with programmable anti scatter and receiving slits as well as programmable divergence slits. This set-up makes the measurement of film thicknesses ranging from below 10 nm up to 200 nm feasible. Grazing incidence reflection as well as diffraction is possible using the BRUKER D8. This diffractometer is set up with a 6-axis eulerian cradle sample stage and we hope in near future to acquire an incident beam monochromator to be able to reach high resolution.

Software for analysis from both PANalytical and BRUKER is available in the x-ray laboratory.

The x-ray facilities are run maintained and run by Dr. K. Fleischer and Dr. K. Rode, but the access to the machines are free to be used by both staff and students from School of Physics and CRANN under the condition of having followed a radiation safety course provided by School of Physics and also diffractometer-specific training.

The available x-ray facilities assure the access to standard characterisation techniques necessary during sample growth optimisation and also the quality control of more standardized samples. It is also possible to use the facilities to undertake more in-depth analysis of the structural properties of both thin films and powders by taking advantage of the on-site knowledge of x-ray diffraction and reflection and the provided software.

FEI Strata DB 235 Dualbeam FIB/SEM

Our System includes:

GIS

Raith ELPHY E-beam and FIB

Lithography Package

Micromanipulator

Auto-FIB

Automated TEM cross section capability

EDAX EDX System

Dual Beam Concept: FIB & SEM operating together.

Optical Magnetometry

Kerr effect setup

Faraday effect setup

Kulicke & Soffa Model 4123 Wedge Bonder

The K&S Model 4123 Wedge Bonder is commonly used to bond various devices ranging from fundamental discrete devices to complex integrated circuits. Aluminium and gold wires are normally used in order to ensure adequate electrical connect between two conducting materials. The bonding process is enabled by ultrasonic energy to provide a strong and reliable connection between the wire and material. Adjustable parameters such as loop height, search height, bond force, bond time and power are frequently optimized depending on the sample. The bonder is also facilitated with a stereo zoom microscope and height adjustable sample holder.

Organic Thermal Evaporator

The organic thermal evaporator consists of two thermal sources made with tungsten filaments, a Q-pod quartz crystal monitor (QCM), a substrate holder with heating capabilities, a shutter, 3 thermocouples and an additional feedthrough for injecting gas. Contamination between the two thermal sources is minimized by the installation of a stainless steel divide. The pressure in this bell jar configuration is maintained by a Pfeiffer Turbo-cube pumping system which is connected through the base plate. The pressure is monitored by a full range compact ion gauge also mounted through the base plate as well. The Q-pod QCM operating at a frequency of approximately 6MHz is controlled by an accompanying software which is connected via USB port to a personal computer (PC). A standard Wayne Kerr AP6050A power supply is used to apply large currents to the thermal sources.